1. Field of the Invention
The present invention relates to a drawing unit and method used in forming a non-woven fabric web structure formed of, for example, synthetic polymer fiber.
2. Description of the Related Art
As disclosed in, for example, Japanese Examined Patent Application Publication No. 49-30861 and Japanese Examined Utility Model Publication No. 63-15346, a conventional drawing unit used in forming a non-woven fabric web structure formed of, for example, synthetic polymer fiber is constructed so that a group of filaments from a spinneret is sucked into one long, thin path where air currents are produced in order to draw the filaments and subject them to an opening process.
However, the air currents produced in the one path of the conventional drawing unit are colliding currents, so that turbulence occurs in the air currents in the path, thereby disturbing the flow of the filaments in the path. This leads to the problem that the state of accumulation of the filaments during a post-processing operation gets adversely affected as a result of, for example, entanglement of the filaments. In other words, this leads to the problem that density spots, for example, are produced in the obtained non-woven fiber web structure as a result of entanglement of the filaments in the path, so that the non-woven fabric web structure cannot be produced with uniform thickness.
In addition, in the conventional drawing unit, when, in order to increase productivity of non-woven fabric web structures, the number of groups of filaments pushed out from the spinneret is increased, the number of groups of filaments sucked into the long, thin path formed in the conventional drawing unit is also increased, thus aggravating the above-described problem that a non-woven fabric web structure with uniform thickness cannot be obtained.
Further, there is another problem. Angles within which groups of filaments are contained at a suction inlet of the conventional drawing unit are such as to cause more frequent occurrences of differences in the fineness of the filament groups from a spinning hole of the outermost row of the spinneret and the fineness of the filament groups from a spinning hole of the center row of the spinneret are made after drawing.
Accordingly, it is an object of the present invention to provide a drawing unit and method capable of producing a non-woven fabric web structure having few density spots and having uniform thickness as a result of reduced entanglement of filaments in a path formed in the drawing unit.
In order to overcome this problem, there is provided a drawing unit for producing a non-woven fabric web, comprising:
a plurality of slits for drawing filaments, in which groups of filaments pushed out from a spinneret divide and are sucked into the plurality of slits in order to be drawn by air currents formed in the slits; and
a collecting conveyor for collecting the filaments blown out from the slits in order to form the non-woven fabric web;
wherein the plurality of slits extend in a widthwise direction of the collecting conveyor, and are disposed substantially parallel to a direction of movement of the collecting conveyor.
By virtue of this structure, it is possible to reduce the number of filaments per slit, and to reduce entanglement of the filaments in each slit, so that a non-woven fabric web with uniform thickness can be obtained. The number of filaments can be increased by increasing the number of slits, so that productivity of non-woven fabric webs can be increased.
The slits may be formed between a first member including an air ejection section and a plate, and between a second member including an air ejection section and the plate, the plate being disposed between the first member and the second member. By virtue of this structure, a width can be adjusted by the thickness of the plate disposed between the first member and the second member. By adjusting the width, the groups of filaments blown out from the slits can join above the collecting conveyor. In other words, the groups of filaments blown out from two slits disposed side by side are brought together inwardly toward each other due to stagnation of air between the two slits in order to join together above the collecting conveyor. This allows a nonwoven fabric web with uniform thickness to be obtained.
An air current adjustor plate may be mounted below the plate. By virtue of this structure, the degree with which the groups of filaments blown out from the two slits disposed side by side are joined can be adjusted, making it possible to obtain a non-woven fabric web with uniform thickness.